Drone with green lights

On this evening I was outside on my phone, when I heard what I thought was a military cargo plane flying over.  It wasn't.  It was a giant drone.  It was black and had green lights on all four arms.  It was very loud.  I could see it was a drone.  It flew over my house and over the mountain it moved very fast.  About 5 minutes later a small private plane flew by in the same direction of the drone.  It scared me.  
A few nights later I could hear the noise of the cargo plane coming.  I ran outside to see and it was the cargo plane but it now has green lights on it.  Very strange.  Cargo planes have red lights.  
Some friends of mine came by last night to visit and they mentioned to me that they were out the other evening and seen a huge drone the size of a full size pickup flying from the high country over to the feilds where I live. It was quiet according to my friends.  It then flew back over the mountain.  The drone I seen was big.  Maybe the size of two full size pickups.